WO2023095284A1

WO2023095284A1 - Pillbox window and method for manufacturing pillbox window

Info

Publication number: WO2023095284A1
Application number: PCT/JP2021/043396
Authority: WO
Inventors: 尚也宗本
Original assignee: キヤノン電子管デバイス株式会社
Priority date: 2021-11-26
Filing date: 2021-11-26
Publication date: 2023-06-01
Also published as: JPWO2023095284A1

Abstract

The present invention includes a circular waveguide with a cylindrical shape, a lead-in side rectangular waveguide, and a lead-out side rectangular waveguide. The circular waveguide includes a dielectric airtight window that partitions an internal space into a lead-in side and a lead-out side and one welding collar disposed on the circumference of an end face of at least one of the lead-in side and the lead-out side. The lead-in side rectangular waveguide and the lead-out side rectangular waveguide are connected to circular connecting plates that are connected to the corresponding end faces of the circular waveguide; and another welding collar to be welded to the one welding collar is provided on the circumference of at least one of the connecting plates. A groove or a hole, into which a rotation restriction jig for restricting rotation in the circumferential direction is fit, is formed in each of the one welding collar and the other welding collar; and the entire circumference of each of the one welding collar and the other welding collar including the groove or the hole is fixed by welding.

Description

Pillbox window and method of manufacturing pillbox window

Embodiments of the present invention relate to pillbox windows and methods of manufacturing pillbox windows.

An input coupler that introduces high-power high-frequency waves into an accelerating cavity maintained in vacuum, and an output circuit that extracts high-frequency power from a power tube such as a klystron. are known as pillbox windows.
The pillbox window has an input rectangular waveguide from a radio frequency source (RF source), a circular waveguide, and an output rectangular waveguide, the circular waveguide having a dielectric A body airtight window (ceramic window) is provided, and the dielectric airtight window separates the lead-in side and the lead-out side.
In such a pillbox window, a sealing structure using a flange and a gasket is known as a sealing structure for each waveguide.

JP-A-7-321501

On the other hand, as another sealing structure for a waveguide in a pillbox window, there is a sealing structure by Tig welding.
In such welding, welding flanges are provided on the waveguides to be joined, respectively, and the welding flanges are fixed by TIG welding. Welding was performed while measuring and controlling the high-frequency transmittance (VSWR) so that the welding collars would not rotate in the circumferential direction and be displaced.
However, the measurement work using each measuring instrument is time-consuming and causes variations in measurement, which adversely affects the electrical characteristics of the electron tube and acceleration tube in which the pillbox is installed.

The present embodiment has been made in view of the above points, and its purpose is to provide a pillbox window that can prevent adverse effects on electrical characteristics and can be easily assembled.

One embodiment includes a cylindrical circular waveguide, a square tube-shaped lead-in side rectangular waveguide that is provided at one end of the circular waveguide and introduces a high frequency from a high frequency source, and the circular waveguide. A lead-out side rectangular waveguide having a rectangular cylindrical shape provided at the end for leading out high frequency waves, the circular waveguide having a dielectric hermetic window, the dielectric hermetic window separating the internal space from the lead-in side to the lead-out side. and has one welding flange on the outer circumference of the end face on at least one side of the introduction side and the extraction side, and the introduction side rectangular waveguide and the extraction side rectangular waveguide are each the above It is connected to a circular connection plate connected to the end face of the circular waveguide, and at least one of the connection plates has on its outer periphery another welding collar welded to the one welding collar, Both the welding collar and the other welding collar are formed with a groove or hole for fitting a rotation restricting jig that restricts rotation in the circumferential direction, and the entire circumferential direction including the groove or hole is It is a welded-in pillbox window.

Another embodiment is the method of manufacturing a pillbox window according to claim 1, wherein the rotation restricting jig is fitted into the holes or grooves of the one welding collar and the other welding collar. It has a fitting convex portion, and the fitting convex portion is attached to the one welding flange and the other welding flange before the one welding flange and the other welding flange are fixed by welding. a rotation restricting step of restricting relative rotation in the circumferential direction by joining together; a torque applying step of tightening the one welding collar and the other welding collar with a torque applying jig to a predetermined torque; After the regulating step and the torque applying step, a first welding step of welding a portion of the one welding flange and the other welding flange excluding the hole or the groove, and after the first welding step, the rotation regulating a jig removing step of removing the jig and the torque imparting jig; and a second welding step of welding the hole or groove portion of the one welding collar and the other welding collar after the jig removing step. and a method of manufacturing a pillbox window.

FIG. 1 is a cross-sectional view of a pillbox window according to a first embodiment. 2 is a sectional view showing the circular waveguide unit shown in FIG. 1. FIG. 3 is a sectional view of the rectangular waveguide unit shown in FIG. 1. FIG. 4A and 4B are views of one and the other welding flanges shown in FIG. 1, where (a) is a perspective view and (b) is a front view. 5A and 5B are views of the rotation restricting jig according to the first embodiment, in which FIG. 5A is a front view, and FIG. 6A and 6B are views showing one welding collar fitted to the lead-in side connecting plate, where (a) is a perspective view and (b) is a front view. 7A and 7B are views showing the other welding flange and lead-out side connecting plate fitted to the circular waveguide, in which FIG. 7A is a perspective view and FIG. 7B is a rear view. FIG. 8 is a cross-sectional view of a pillbox window assembly having a rotation restricting jig and a torque imparting jig according to the first embodiment. FIG. 9 is a cross-sectional view showing an example of an application of a pillbox window, where (a) the pillbox window is installed in front of the cavity, and (b) the pillbox window is installed vertically into the cavity. FIG. 3 is a cross-sectional view showing an example of an assembly that 10A and 10B are views of one welding flange and the other welding collar according to the second embodiment, where (a) is a perspective view and (b) is a front view. 11A and 11B are views of the lead-in side connection plate, in which FIG. 11A is a perspective view and FIG. 11B is a front view. 12A and 12B are views of a rotation restricting jig according to the second embodiment, in which FIG. 12A is a front view and FIG. 12B is a side view. FIG. 13 is a cross-sectional view of a pillbox window assembly having a rotation restricting jig and a torque imparting jig according to the second embodiment. FIG. 14 is a diagram showing the rotation angle of the outlet side with respect to the inlet side in the pillbox window. FIG. 15 is a graph showing the relationship between the design frequency and the VSWR for each rotation angle. FIG. 16 is a graph showing the relationship between rotation angle and VSWR. FIG. 17 is a graph showing the relationship between VSWR and cavity parameter characteristics (f, R, Q) in cavities of the same shape.

An embodiment will be described in detail below with reference to the drawings. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual embodiment, but this is only an example, and the embodiment of the present invention. It does not limit interpretation. In addition, in this specification and each figure, the same reference numerals are given to components that exhibit the same or similar functions as those described above with respect to the previous figures, and redundant detailed description may be omitted as appropriate. .

First, the first embodiment will be described with reference to FIGS. 1 to 9 and 11. FIG.
As shown in FIG. 1, the pillbox window 1 according to the first embodiment includes a cylindrical circular waveguide 3 and a square cylindrical lead-in rectangular waveguide 5 for introducing high frequency waves from a high frequency source. , and a derivation-side rectangular waveguide 7 in the shape of a rectangular tube for deriving high frequencies.
The circular waveguide 3 has a cylindrical shape, and a circular dielectric hermetic window (ceramic window) 9 is connected to the inside of the cylinder. The dielectric hermetic window 9 transmits a predetermined high frequency, and divides the internal space of the circular waveguide 3 into an introduction side and an extraction side.
The circular waveguide 3 includes a circular waveguide and a circular waveguide having an additional structure such as a cooling structure.
A circular lead-in side connection plate 11 is connected to the lead-in end of the circular waveguide 3, and a circular lead-out side connection plate 13 is connected to the lead-out end.
An introduction-side rectangular waveguide 5 is connected to the center of the introduction-side connection plate 11 , and an extraction-side rectangular waveguide 7 is connected to the center of the output-side connection plate 13 .

One ring-shaped welding flange 15 is connected to the outer circumference of the introduction-side connection plate 11 , and the other ring-shaped welding flange 17 is connected to each outer circumference of the introduction-side end of the circular waveguide 3 . ing.
As shown in FIGS. 1 and 4, the one welding collar 15 and the other welding collar 17 are shaped so that the portions to be welded have the same structure, and are of the same type. The

welding collars

15 and 17 are made of metal such as stainless steel plated with Ni (nickel) or the like.
Since the welding flanges 15 and 17 on one side and the other have the same construction, only one welding flange 15 will be described below.
One welding flange 15 has an inner peripheral side portion 19 and an outer peripheral side portion 21, and the thickness W1 (see FIG. 1) of the inner peripheral side portion 19 is replaced by the thickness W2 (see FIG. 1) of the outer peripheral side portion 21. ). The inner peripheral side portion 19 of one welding flange 15 is connected to the outer peripheral surface of the introduction side connection plate 11 , and the inner peripheral side portion 19 of the other welding flange 17 is connected to the outer peripheral surface of the circular waveguide 3 . are doing.
As shown in FIG. 4, a plurality of holes 22 are formed in the outer peripheral side portion 21 at intervals in the circumferential direction. In this embodiment, three holes 22 are formed at regular intervals.
The inner peripheral side portion 19 is formed with a fitting convex portion 19a protruding toward the inner peripheral side. As shown in FIG. 6, the fitting protrusion 19a is fitted to the fitting recess 11b (see FIG. 11) formed in the lead-in side connection plate 11 for positioning. The position in the rotational direction may be adjusted only by marking lines K, which will be described later, without providing the fitting concave portion 11b.

As shown in FIG. 1, one welding collar 15 and the other welding collar 17 are arranged to face each other, and the facing surface 23 is a flat surface, and the inner peripheral side 19 to the outer peripheral side 21 are arranged to face each other. It has a dimension H spanning
The connection of each member described above is performed using a metal brazing material.

One welding flange 15 and the other welding flange 17 have opposing surfaces 23 butted against each other, and the outer peripheral edge thereof is welded and fixed by a welding portion 25 . Welding is, for example, arc welding.
The welded portion 25 is also welded to each hole 22 by filling the hole 22 .

Next, a method for manufacturing the pillbox window 1 according to this embodiment will be described.
As shown in FIGS. 2 and 3, the pillbox window 1 of this embodiment includes two units 31, a circular waveguide unit 31 (see FIG. 2) and a rectangular waveguide unit 33 (see FIG. 3). , 33 are respectively assembled, and these

units

31 and 33 are welded and fixed by the welding portion 25 (see FIG. 1).

As shown in FIG. 2, a dielectric airtight window 9 is attached to the inner peripheral surface of the cylindrical circular waveguide 3, the other welding flange 17 is fitted to the outer peripheral surface of the introduction side end of the circular waveguide 3, A circular waveguide unit 31 is assembled by attaching a lead-out side connection plate 13 fitted with a lead-out rectangular waveguide 7 to the lead-out side end of the circular waveguide 3 .
As shown in FIG. 7, the fitting position of the other welding flange 17 and lead-out side connection plate 13 with respect to the circular waveguide 3 is based on the fitting portion 7a of the lead-out rectangular waveguide 7 (see FIG. 1). Assembly is carried out based on at least two marking lines K (indicated by dashed lines in the drawing), or at least two recesses (or projections) 13b (there are three in the drawing) are formed in each part through holes 22. The marking line K of the circular waveguide 3, the marking line K of the welding flange 17 on the other side, and the marking line K of the lead-out side connection plate are aligned with each other, and the circular waveguide 3 Positioning in the rotational direction is performed according to the machining dimensions of each part.
With respect to the circular waveguide unit 31 (see FIG. 2) assembled in this way, each attached member is connected by metal brazing.

As shown in FIGS. 3 and 6, the rectangular waveguide unit 33 is formed by welding one end to the outer circumference of the introduction-side connection plate 11 in which the introduction-side rectangular waveguide 5 (not shown in FIG. 6) is fitted. Assemble by fitting the brim 15 for use. The fitting position of one welding flange 15 with respect to the lead-in side connecting plate 11 is based on at least two marking lines K (indicated by broken lines in the figure) with reference to the fitting portion 5a of the lead-in rectangular waveguide 5. Alternatively, by fitting the fitting concave portion 11b of the lead-in side connecting plate 11 and the fitting convex portion 19a of one of the welding flanges 15, positioning in the rotational direction is performed according to the machining dimensions of the parts.
For the rectangular waveguide unit 33 assembled in this way, each attached member is connected by metal brazing.

Next, as shown in FIG. 8, the circular waveguide unit 31 and the rectangular waveguide unit 33 are aligned, joined with a predetermined torque, and fixed by welding. Therefore, the rotation restricting jig 35 and the torque applying jig 37 will be described.
As shown in FIG. 5, the rotation restricting jig 35 includes a ring-shaped jig main body 35a and a fitting protrusion 35b. The jig main body 35a is formed in a shape overlapping the outer peripheral side portion 21 of one welding flange 15 (see FIG. 8). The fitting protrusion 35b is a pin that fits into the holes 22 (see FIG. 4) formed in the one and the

other welding collars

15 and 17, and protrudes from one surface of the jig main body 35a.
In this embodiment, the fitting protrusions 35b are provided at three locations at equal intervals in the circumferential direction of the jig body 35a.

As shown in FIG. 8, the torque applying jig 37 is composed of a pair of holding

bodies

39a and 39b, a torque restricting member 41, and a tightening tool 43. As shown in FIG. The torque applying jigs 37 are provided at three positions corresponding to the positions of the fitting projections 35b of the rotation restricting jig 35. As shown in FIG.
Of the pair of clamping

bodies

39a and 39b, one clamping body 39a is placed in contact with the lead-in side surface 11a of the lead-in side connection plate 11, and the other clamping body 29b is arranged in contact with the lead-out side face 13a of the lead-out side connection plate 13. As shown in FIG.
The torque regulating member 41 has a lead-in side end 41a and a lead-out side end 41b with diameters smaller than that of an intermediate part 41c. The lead-in side end portion 41a and the lead-out side end portion 41b are movably inserted into the corresponding insertion holes of the lead-in side connection plate 11 and the lead-out side connection plate 13, respectively. As a result, when the distance between the lead-in side connecting plate 11 and the lead-out side connecting plate 13 becomes narrower than a predetermined value, the intermediate portion 41c is brought into contact with the intermediate portion 41c to restrict the applied torque from becoming excessive.
The fastener 43 includes a threaded shaft 43a which is entirely threaded, and nuts 43b which are screwed onto both ends of the threaded shaft 43a. 11 and lead-out side connection plate 13 .
Then, the torque applying jig 37 applies a predetermined torque by tightening the nut 43b.

Next, alignment between the circular waveguide unit 31 (see FIG. 2) and the rectangular waveguide unit 33 (see FIG. 3) will be described.
As shown in FIG. 8, the other welding flange 17 (see FIG. 2) fixed to the circular waveguide unit 31 and the one welding flange 15 (see FIG. 3) fixed to the rectangular waveguide unit 33 are butted against each other. Then, the holes 22 (see FIG. 4) of the

welding collars

15 and 17 are aligned with each other, and the fitting protrusion 35b of the rotation restricting jig 35 is fitted into the holes 22 of the

welding collars

15 and 17. As shown in FIG. As a result, the rotation of one welding flange 15 of the circular waveguide unit 31 and the other welding flange 17 of the rectangular waveguide unit 33 is restricted (rotation restriction step).
After that, one holding member 39a is applied to the introduction side surface 11a of the introduction side connection plate 11, and the other holding member 39b is applied to the outlet side surface 13a of the outlet side connection plate 13. One holding member 39a and the other holding member 39b A torque restricting member 41 and a screw shaft 43a are inserted between them.
Next, the screw shaft 43a is tightened with the nut 54b, and the one welding flange 15 and the other welding flange 17 are butted against each other with a predetermined torque (torque application step).

After that, the outer peripheral side portions 21 of the one welding flange 15 and the other welding flange 17 excluding the hole 22 are fixed by welding (first welding step).
Next, the nut 43b is loosened, the torque applying jig 37 is removed, and the rotation restricting jig 35 is removed (jig removing step).
After that, the holes 22 (see FIG. 4) of one welding flange 15 and the other welding flange 17 and their surroundings are welded (second welding step). A welding rod having the same diameter is inserted into the hole 22 for welding.

Effects of the first embodiment will be described.
According to the first embodiment, the one welding collar 15 and the other welding collar 17 are restricted from rotating in the circumferential direction by the rotation restricting jig 35 (see FIG. 5) fitted in the hole 22. Since welding is performed in this state, it is possible to prevent phase shift in the rotational direction during welding.
Further, since the hole 22 of one welding flange 15 and the other welding flange 17 is welded after the rotation restricting jig 35 is removed, the one welding flange 15 and the other welding flange 17 are welded together. It is possible to reliably perform vacuum sealing over the entire circumference.
Since the rotation restricting jig 35 prevents rotational deviation and the torque imparting jig 37 allows the pillbox window 1 to be manufactured with a predetermined torque, adverse effects on electrical characteristics can be prevented and assembly can be easily performed.

Thus, the assembled pillbox window 1 (see FIG. 1) can prevent the rotation angle (deviation) θ (see FIG. 14) of the lead-out rectangular waveguide 7 with respect to the lead-in rectangular waveguide 5, and the rotation angle (Displacement) θ could be limited to 1° or less.

That is, the pillbox window 1 (see FIG. 1) may be installed horizontally with respect to the cavity 50 as shown in FIG. When installed horizontally in FIG. 9A, the lead-in rectangular waveguide 5 and lead-out rectangular waveguide 7 should be parallel with a level or the like. When assembled under management and installed vertically as shown in FIG. 9(b), it is impossible to measure with a spirit level and the like, and it is installed only visually. At that time, the high-frequency transmittance (VSWR) must be measured and managed for assembly and installation. However, according to the pillbox window 1 according to the present invention, the cause of the error in the rotational direction of the lead-in rectangular waveguide 5 and lead-out rectangular waveguide 7 is the hole 22 of the welding flange 17 and the jig body 35a. It is possible to limit the error to pin diameter errors and component tolerances or scribe line tolerances, and it is possible to reliably limit mounting deviation (error) θ in the rotational direction to 1° or less. As a result, fluctuations in the high frequency transmittance (VSWR) can be suppressed within ±0.01 of the design value, and the quality of the cavity 50 connecting the pillbox windows can be stabilized.

Here, with reference to FIGS. 14 to 17, the relationship between the shift angle (rotational angle) θ between the introduction-side rectangular waveguide 5 and the extraction-side rectangular waveguide 7 and the fluctuation of the high-frequency transmittance (VSWR). will be explained.
FIG. 14 shows the deviation angle θ in the rotational direction between the lead-in rectangular waveguide 5 and lead-out rectangular waveguide 7 .
FIG. 15 shows the rotation positions when the shift angle θ is 0, 2.5°, 5°, 7.5°, and 10°. FIG. 10 shows simulation results of frequency dependence of VSWR; FIG. In FIG. 15, the horizontal axis is the frequency f and the vertical axis is the VSWR, showing the installation angle dependency of the VSWR on the design frequency. FIG. 16 plots each VSWR at the design frequency shown in FIG. 15, with the shift angle (rotation angle) θ on the horizontal axis and the VSWR on the vertical axis.
From these FIGS. 15 and 16, it can be seen that as the shift angle (rotation angle) .theta. increases, the VSWR greatly varies from the reference 1.

FIG. 17 shows the Q value (quality value) of the cavity parameter and the shunt impedance when the geometric structure of the cavity 50 (see FIG. 9) is constant and the VSWR of the dielectric airtight window (RF window) 9 (see FIG. 1) is varied. Graphs of values normalized to 1 are shown for R and resonance frequency f, respectively, with VSWR=1. The horizontal axis represents VSWR, and the vertical axis represents relative ratios of f, R, and Q.

From these results, the VSWR of the pillbox window 1 (see FIG. 1) changes depending on the installation angle (deviation angle) θ in the rotational direction of the lead-out rectangular waveguide 7 with respect to the lead-in rectangular waveguide 5, as shown in FIG. As shown, it can be confirmed that the fluctuation of the VSWR of the pillbox window greatly affects the Q value and the shunt impedance R of the cavity 50 .

Therefore, according to the pillbox window 1 of the present embodiment, since the shift angle θ can be suppressed within 1°, the fluctuation of VSWR caused by the shift angle θ in the rotational direction is suppressed within ±0.01. At the same time, it is possible to finish with a certain quality without spending time on assembly.

Other embodiments will be described below. In the embodiments described below, portions having the same effects as those of the above-described first embodiment are denoted by the same reference numerals. Detailed description is omitted.
A second embodiment will be described with reference to FIGS. 10 to 13. FIG.
As shown in FIG. 10, in this second embodiment, grooves 24 are formed in the

welding flanges

15 and 17 on one and the other side instead of the holes 22 of the first embodiment.
The grooves 24 are formed in the shape of rectangular depressions, and in this embodiment, are formed at three locations at equal intervals in the circumferential direction.
As shown in FIG. 11, the lead-in connection plate 11 has at least two marking lines K (broken lines in the drawing) with reference to the fitting portion 5a of the lead-in rectangular waveguide 5, as in the first embodiment. ) are formed, and one marking line is formed at a position corresponding to the fitting recess 11b.

As shown in FIG. 12 , the rotation restricting jig 35 includes a plate-like jig body 35 a and a fitting protrusion 35 b that fits into the groove 24 . An arcuate portion 35c along the outer periphery of the

welding collars

15 and 17 is formed in the jig body 35a. The fitting protrusion 35b is formed so as to protrude from the arcuate portion 35c.
The jig main body 35a has a large-diameter regulation member insertion hole 45a through which the intermediate portion 41c (see FIG. 13) of the torque regulation member 41 is inserted, and a screw shaft 43a (see FIG. 13) of the fastener 43. A small-diameter screw shaft insertion hole 45b is formed.

In the manufacturing method of the pillbox window 1 according to the second embodiment, as shown in FIG. The fitting protrusions 35b of the rotation restricting jig 35 are fitted into the opposing

grooves

24, 24 from the outer peripheral side of the

welding flanges

15, 17. As shown in FIG.

Next, the screw shaft 43a is inserted through the screw shaft insertion hole 45b (see FIG. 12) of the jig body 35a, and the intermediate portion 41c of the torque regulation member 41 is inserted through the regulation member insertion hole 45a (see FIG. 12). The clamping member 39a is arranged on the lead-in side surface 11a of the lead-in side connection plate 11, and the other clamping member 39b is arranged on the lead-out side surface 13a of the lead-out side connection plate 13, so that torque regulating members corresponding to the

clamping members

39a and 39b are provided. The ends 41a and 41b of the screw shaft 41 are inserted, and the end of the screw shaft 43a is inserted and tightened with a nut 43b.
After that, similarly to the first embodiment, the grooves 24 (see FIG. 10) of the

welding collars

15 and 17 and their surroundings are welded (first welding step), and then the torque imparting jig 37 and the rotation restrictor are welded. The jig 35 is removed from the welding flanges 15, 17 (jig removal step), and the grooves 24 (see FIG. 10) of the

welding flanges

15, 17 and their surroundings are welded (second welding step).
According to this 2nd Embodiment, there can exist an effect similar to 1st Embodiment mentioned above.

The above-described embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

For example, the number of holes 22 and grooves 24 formed in the

welding collars

15 and 17 is not limited to three, and may be formed in any number such as four or six in the circumferential direction. Moreover, the shape of the hole 22 is not limited to a circle, and may be rectangular or hexagonal, and the shape is not limited. Similarly, the groove 24 is not limited to being rectangular, and may be arcuate.

Claims

A cylindrical circular waveguide, a square cylindrical lead-in rectangular waveguide provided at one end of the circular waveguide for introducing high frequency from a high frequency source, and a high frequency provided at the other end of the circular waveguide. and a derivation-side rectangular waveguide having a square tubular shape for deriving the
The circular waveguide has a dielectric hermetic window, which divides the internal space into an inlet side and a lead-out side with the dielectric hermetic window. having one welding collar,
The lead-in rectangular waveguide and the lead-out rectangular waveguide are connected to circular connection plates connected to end faces of the circular waveguides, respectively, and at least one of the connection plates having the other welding collar welded to the welding collar of
Both the one welding collar and the other welding collar are formed with a groove or hole for fitting a rotation restricting jig that restricts rotation in the circumferential direction, and the circumferential direction including the groove or hole is formed. A pillbox window that is welded throughout.
2. The method of manufacturing a pillbox window according to claim 1, wherein said rotation restricting jig has fitting protrusions that fit into said holes or grooves of said one welding flange and said other welding flange. Then, before the one welding flange and the other welding flange are welded and fixed, the fitting convex portion is fitted to the one welding flange and the other welding flange and relatively a rotation regulating step for regulating rotation in the circumferential direction;
a torque applying step of tightening the one welding collar and the other welding collar with a torque applying jig to a predetermined torque;
a first welding step of welding portions of the one welding collar and the other welding collar excluding the hole or the groove after the rotation restricting step and the torque applying step;
A jig removing step of removing the rotation restricting jig and the torque applying jig after the first welding step;
A method of manufacturing a pillbox window, comprising a second welding step of welding the hole or groove portion of the one welding collar and the other welding collar after the jig removing step.